C0740: Electric Power Steering Voltage Supply
The supply voltage to the EPS module is out of range, reducing or disabling power assist.
What C0740 means
C0740 is a generic OBD-II chassis code in the steering group.
- Check engine light
- Usually off
- Emissions-related
- No
- Limp mode possible
- Not typical
- Drive cycle to clear
- Not required
Get it fixed
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Symptoms
- ABS warning light on
- ESC/stability control deactivated
- Possible reduced brake assist
- Speedometer may behave erratically
Common causes
- 01Battery undervoltage during high steering loadMost likely
- 02Ground point corrodedPossible
Can I drive with C0740?
Drive carefully and get it checked soon.
Steering assist may drop out, making the wheel heavy at low speed. Avoid driving if steering becomes very heavy or erratic.
Why we rate it urgent
- Steering assist may be reduced or lost
- Usually lights the ABS, traction or stability warning instead of the check engine light
Severity is our rule-based rating from the code’s flags in OBDex and the system it affects, not an inspection of your car. If the check engine light is flashing, or you notice overheating, low oil pressure, or brake or steering problems, stop driving and get help.
How to diagnose C0740
- 1
Confirm the code and save freeze-frame data
Read the codes with an OBD-II scan tool and note every code, not just C0740. Save the freeze-frame data (speed, load, temperature when the fault set) before clearing anything; it tells you when the fault happens.
- 2
Fix other faults first
If other codes are stored, start with power-supply, sensor-circuit and communication codes. They can cause this code as a side effect.
- 3
Test the circuit
Inspect the wiring and connector at the eps control module and power supply wiring for damage, corrosion or chafing. With a multimeter, check supply voltage, ground and signal against the specifications in the service manual for your vehicle.
- 4
Test the likely causes in order
Start with the most likely cause and work down: Battery undervoltage during high steering load; ground point corroded. Test before replacing parts.
- 5
Check for recalls and service bulletins
Look up recalls for your exact vehicle with its VIN, and ask a dealer about technical service bulletins (TSBs). Manufacturers sometimes issue software updates or extended warranties for known faults.
- 6
Clear the code and verify the repair
After the repair, clear the code and drive the car under the conditions in the freeze-frame data to confirm it does not return.
C0740 repair cost estimate
Estimate, not a quote. Labor times are typical ranges for this code from OBDex, and $125/hr is an assumed rate. Shop rates and labor times vary by vehicle and region. Diagnosis time may be billed separately.
- DIY difficulty
- Moderate
- Good DIY job?
- Yes, with a scan tool
Needs a scan tool and some experience with testing.
Parts and systems involved
- EPS control module
- Power supply wiring
- Battery
C0740 FAQ
What does C0740 mean?
C0740 means “Electric Power Steering Voltage Supply”. The supply voltage to the EPS module is out of range, reducing or disabling power assist.
Is C0740 serious? Can I keep driving?
We rate C0740 as urgent severity. Drive carefully and get it checked soon. Steering assist may drop out, making the wheel heavy at low speed. Avoid driving if steering becomes very heavy or erratic.
What causes C0740?
The most common causes, from most to least likely: Battery undervoltage during high steering load; Ground point corroded. Test before replacing parts, because several causes can set the same code.
How much does it cost to fix C0740?
Typical labor is about $65–$250 at an assumed $125/hour shop rate, plus parts. That is an estimate, not a quote: labor times and rates vary by vehicle and region, and diagnosis may be billed separately.
Can I fix C0740 myself?
DIY difficulty is moderate. Many owners can handle it with a scan tool, a multimeter and basic hand tools. Always confirm the cause before buying parts.
Will C0740 clear itself?
If the fault was intermittent, the warning may go off once the computer stops seeing it, but the code stays in memory. Fix the cause; clearing the code alone doesn’t repair anything.